1. Long silence / delayed reply
Almost like you don't intend to respond.
Disarms your opponent. Makes them second-guess themselves. Gives you time to think.
Guilt begins to fester in your opponent's insides. Let them be uncomfortable in this silence.
2. Greeting that is open to (mis)interpretation
If your opponent interprets it negatively, it's their misinterpretation, their fault, not yours. If they interpret it positively, you act like, "But of course!"
3. Suggested solution where your opponent, not you, is the actor
Shows you're action-oriented, solution-focused, not a bickering, handwashing weasel. If the problem happens again, it's your opponent's fault. They're supposed to be the actor in the solution.
4. Parenthetical hint that it's not your fault, that you couldn't have done any better given the circumstances
Sandwiched within an actionable recommendation, it doesn't make you sound like you're making excuses. But your opponent gets the suggestion, and you show you're not a pushover.
Amplifies the impact of your response: "Here's someone who had absolutely no hand in the root-cause of this problem, still trying to solve it like she owns it. Isn't she great?"
5. Another suggested solution where your opponent, not you, is the actor
Your opponent will go: "What? Another solution I should have thought of and done before? I'm an asshole for blaming her."
6. Self-deprecating statement that absolves you from this trouble
You're not a proud weasel. You're just a humble, lowly bystander who got caught in this crossfire. For someone who's just a bystander, you're going way above the call of duty. What an angel you are.